Why cheap USB Serial adapters does NOT work well.

The Short Explanation.
Many low-cost USB to Serial adapters does not work well with newer operating systems such as Windows 10, Windows 8 and Windows 7 and because these adapters are made with a low-cost
processor chip meeting only a minimum of the industry's standard
requirements. The physical quality of the chip is usually fine however
the drivers for the chipset are often poorly written programs which makes
the adapter unstable and unreliable and not fully compatible with
Windows 8 and other current operating systems. Because of this you will
in most cases be unable to make a low-cost adapter work well with Windows 10, Windows 8, Windows 7
and Vista, especially the 64-bit versions, and you can expect some of
the following typical errors:

This is the reason why we highly recommend that you spend a few dollars extra on a higher quality adapter such as one of these below. It will ultimately save you a lot of time and headache. We recommend one of the following adapters:

The long technical explanation.
Most low-cost USB to Serial adapters (also called USB to RS232 adapters
or converters) are not "true serial", they handle only approximately
60% of the 'common' RS232 uses/devices, which means that they will only
work with slightly more than half of all commonly used serial devices
such as printers, GPS units, handheld devices, scales, cameras and
other typical serial devices.

Other problems you might experience with a low-cost
adapter.
Due to latencies (data delays) and the way data is transmitted, a USB adapter cannot be 100% transparent to the device you are connecting to your computer, so among other
things successful communication is a matter of timing between data sent from your computer, converted by the adapter and then received by your serial device. If this timing is off just slightly you will be unable to communicate successfully.
Many programs and devices were written and constructed for a serial
port having a 16-character FIFO - or possibly for the original serial
port that didn't have any FIFO at all. Several USB adapters have
hundreds of bytes of FIFO, so it matters a lot if the data is sent
using bulk transfers, and if the device is using any type of control
transfer. This scenario is giving many low-cost adapters bad timing
issues with many programs and devices, which in general means that it
won't work properly with either your computer or the device you connect
to the adapter.

USconverters.com do sell a low-cost adapter for customers who wish to
use it with Windows 98, 2000 and XP, (here is an overview of all our USB to Serial RS232 adapters ) however for Windows 10, 8 or 7 an Ultimate, Premium or Professional grade adapter such as one of these shown above is highly recommend.

What is limited compatibility?
Since most low-cost USB to Serial adapters are using a low-cost
processor chip, these has only limited compatibility with Windows Vista
and Windows 10 / 8 / 7. Limited compatibility means that either the adapter or the driver
might or might not work with your Windows 10 / 8 / 7 computer, it all depends on
your computer's particular hardware, installed Windows components and
service packs, conflicting drivers and other pheriphial devices, and
even your processors bios version.
A high-quality adapter with well-written drivers address all these factors which are hard-coded into the drivers and makes sure that all these processes, timing, hardware and everything else goes smooth so you can communicate with your serial device properly.